Objectives: To compare the coronary heart disease risk among patients with rheumatoid arthritis (RA) initiating common biologic disease-modifying antirheumatic drugs of different mechanisms. Methods: We conducted a retrospective cohort study of patients with RA enrolled in Medicare, a public health plan covering >90% of US residents 65 years or older, from 2006 to 2012 who (1) initiated a biologic, (2) had complete medical and pharmacy coverage for at least 12 months before biologic initiation and (3) were free of coronary heart disease at the time of initiation. We compared the incidence rates (IRs) of (1) acute myocardial infarction (AMI) and (2) a composite outcome of AMI or coronary revascularisation and used multivariable adjusted Cox regression models to examine the associations between the type of biologic and the two outcomes. Results: We identified 47 193 eligible patients with RA with mean age 64 (SD 13) years; 85% were women. Crude IRs for AMI ranged from 5.7 to 8.8 cases per 1000 person-years (PYs). AMI risk was significantly elevated among antitumour necrosis factor (anti-TNF) initiators overall (adjusted HR (aHR) 1.3; 95% CI 1.0 to 1.6) and individually among etanercept (aHR 1.3; 95% CI 1.0 to 1.8) and infliximab (aHR 1.3; 95% CI 1.0 to 1.6) compared with abatacept initiators. Crude IRs for the composite outcome ranged from 7.6 to 14.5 per 1000 PYs. Tocilizumab initiators were at reduced risk of the composite outcome compared with abatacept initiators (aHR 0.64, 95% CI 0.41 to 0.99). Discussion Findings from this observational study of patients with RA suggested that anti-TNF biologics may be associated with higher AMI risk compared with abatacept.